#include "stdinc.h"
#include "HashBloom.h"

#include <cmath>

#include "MerkleTree.h"

size_t HashBloom::get_k(size_t n, size_t h)
{
	for (size_t k = TTHValue::BITS / h; k > 1; --k)
	{
		uint64_t m = get_m(n, k);
		if (m >> 24 == 0)
		{
			return k;
		}
	}
	return 1;
}

uint64_t HashBloom::get_m(size_t n, size_t k)
{
	uint64_t m = (static_cast<uint64_t>(ceil(static_cast<double>(n) * k / log(2.))));
	// 64-bit boundary as per spec
	return ((m + 63) / 64) * 64;
}

void HashBloom::add(const TTHValue& tth)
{
	for (size_t i = 0; i < k; ++i)
	{
		bloom[pos(tth, i)] = true;
	}
}

bool HashBloom::match(const TTHValue& tth) const
{
	if (bloom.empty())
	{
		return false;
	}
	for (size_t i = 0; i < k; ++i)
	{
		if (!bloom[pos(tth, i)])
		{
			return false;
		}
	}
	return true;
}

void HashBloom::push_back(bool v)
{
	bloom.push_back(v);
}

void HashBloom::reset(size_t k_, size_t m, size_t h_)
{
	bloom.resize(m);
	k = k_;
	h = h_;
}

size_t HashBloom::pos(const TTHValue& tth, size_t n) const
{
	if ((n + 1)*h > TTHValue::BITS)
	{
		return 0;
	}
	
	uint64_t x = 0;
	
	size_t start = n * h;
	for (size_t i = 0; i < h; ++i)
	{
		size_t bit = start + i;
		size_t byte = bit / 8;
		size_t pos = bit % 8;
		
		if (tth.data[byte] & (1 << pos))
		{
			x |= (1i64 << i);
		}
	}
	return x % bloom.size();
}

void HashBloom::copy_to(ByteVector& v) const
{
	v.resize(bloom.size() / 8);
	for (size_t i = 0; i < bloom.size(); ++i)
	{
		v[i / 8] |= bloom[i] << (i % 8);
	}
}
